I recently bought a 7 series BMW, and when my uncle noticed how large the truck is, he mentioned that he has a great stereo system I could put in it. What he has is two Rockford Fosgate 150HD amps one powers two 12 inch Rockford Fosgate subs in a box along with a set of speakers for mid and high which is obviously power by the other amp. I am not sure if I remember correctly, but the speakers were two 5 inch Rockford Fosgates, two 4 inch Rockford Fosgates, two 4 inch of another brand, then two Rockford Fosgate tweeters, and two tweeters of that other brand. He said he probably bought it all in the early 90's just as a reference for age. This is obviously assuming it all still works.

You need to confirm that the 150HD amps work. IF they work, you need to pull the covers and look for corrosion from leaked electrolytic caps. This is a VERY common problem and can make the amp time consuming or expensive to repair (if you don't repair it yourself).